Operating slide-valves in dibect-action engines



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GEO. W. HUBBARD, OF BROOKLYN, AND VWILLIAM E. CONANT, OF GREENPOINT, NEW YORK.

OPERATING SLIDE-VALVES IN DIRECT-ACTION ENGINES. l

Specification-forming part of :Letterslatent gNo. 12,203, dated -January 9, 1855; Reissued SeptemberflS, 1869, No. 2,359.

To all whom t may concern:

Be it known'that we, GEORGE. W. HUBBARD, of Brooklyn, in the county of Kings and State of New York, and VILLIAM C0- NANT, of Greenpoint, in the county andState aforesaid, have invented a new and Improved Valve-Motion vfor Direct-Action Engines; and we do hereby decl'arejthat the following isa full, clear,.andfexactzdescription of the same, reference being had to the accompanying drawings, forming part of this specification, in whichf Figures l and 2 are two longitudinal central sections of a double -actingsteam engine having our improved valve motion applied,

showing the position of the valve and its appendages at different stages of the operation of the engine.

Similar letters of reference indicate co-rrespending parts in both figures.

In double acting direct action engines, whose power is transmit-ted directly from the piston rod without producing any rotary motion, and consequently not employing a iiy wheel, considerable difficulty is experienced from the difficulty of obtaining some perfect means of operating the slide valve, for when driven by an arm on the piston rod acting on tappets the steam is out off when the valve has only made one half the necessary movement for reversal and if the resistance is great the piston then stops and as it can move the valve no farther some other means are required to complete the stroke of the valve to open the port for reversal. Most of the means employed for that purpose have from some causes been imperfect.

This invention consists in certain eective means hereinafter described of carrying the valve past the center to open the port to its full width for reversal.

A, is the cylinder ofthe engine; B, the piston; C, vthe piston rodg- D, the steam chest; E, the slide valve; F, the slide valve rod; a, a, the tappets on the valve rod, and b, the tappet arm on the piston rod. All the above parts are of the usual form and construction, except that t-he valve is not rigidly connected with its rod, but contains a recess c, that receives a hook or projection d, o-n the rod, which hook or projection is made shorter than the recess in order that the valve may be allowed to move some distance without the rod.

The valve is connectedl withthe piston rod e, of a piston f', working in a very small steam cylinder g, which is contained within the steam chest D. This cylinder Lislpacked closely at each end and has `two ports z', z', above, or on either side foradmitting steam to it vfrom the steam chest and anfe'xhaust port-'0, for exhaust-ing it, such admission and exhaustion of steam lbeing controlled by a valve 7L, working over the said ports andia cut off plate j, working on the backofft-he valve 't0 Open and close two passages 7c, k,

which are made in it for the admission of steam tothe ports z', z'. 'The valve L,-is connected by a rod n, with the valve rod F. The out off plate merely rests upon the slide valve and the length (if its movement is controlled by two fixed stops Z, Z, the length of movement allowed being equal to half the length of stroke of the main slide valve E, minus the length of the ports in the small cylinder and slide valve. The amount of play allowed to the hook Z of the main slide valve rod F, in the recess o, in the valve E, is equal to the aforesaid length'of movement allowed to the cut off plate.

To describe the manner in which the valve E, is operated we will first suppose the steam port m, of the engine to be open and the engine piston B, to have so nearly finished its stroke to the right, that the tappet arm o, is just coming in Contact with the tappet a to move the valve to eect the reversal, as represented in black outline in Fig. l. this time the ports i, z', of the small cylinder are closed, and so have been from the commencement of the stroke of theengine pist0n B. The piston B will continue its motion beyond the above point until it brings the valve E, to a central position over the ports as shown in red outline in F ig. 1, when, both steam ports being closed, the motion of the piston ceases, and the motion of the valve E, would cease also, but that in moving from the black to the red positions aforesaid, the valve rod F, moves the small valve 71 and opens the port z', to admit `steam At y to the small cylinder g, to act on the piston is moving from end to end of the recess 0, but just before the stroke of the valve E, is completed the end of the recess comes in Contact with the said projection or hook and the remainder of the stroke causes the valve L, to be moved far enough for its passage la, to be closed by the cut oli j, the movement of the valve E, ceases. The ports v1, z', of the cylinder g, remains closed and the valve E, Stationary and all the valve gear in the condition represented in Fig. 2, until the engine piston in its movement to the left brings the tappet arm into contact with the tappet` a, when the valve E, is operated upon in a manner in every respect precisely the reverse of that herein above described, which will be readily understood. The ports 7l, i', are made of such width where they enter the cylinder g, and are in such position that the piston f, at the instant the cutting o' is effected just passes the edge of the opposite port to that through which the steam has been entering` the cylinder to drive it, and so allows the steam in the cylinder to eX- haust. This is illustrated best in Fig. 2, where the port z', is supposed to be justclosed, and the steam which has just acted on the piston is exhausting" through i. The opening from the valve cylinder g, into the latter port though necessarily very small, is wide enough, as nearly the whole time `oc cupied by the movement of the engine pist0n is allowed for the exhaustion of the valve cylinder.

What we claim as our invention and desire to secure by Letters Patent is- Connecting the slide valve E, and its tappet rod F, in such a way as to allow either a certain amount of motion independently of the other, and combining them with a ysteam cylinder g, piston f, slide valve h, and cut off j, so as to operate substantially in the manner herein described.

GEO. W. HUBBARD. WILLM. E. CONANT. Witnesses:

S. H. WALES, I. Gr. MASON.

[FIRST PRINTED 1913.] 

